Glider pickup device



De@ l5, 947 R. B. COTTON 2,432,508

y GLIDER PIK-UP DEvIE Filed oct. 28, 194s 5 sheets-sneet 1..

5 Sheets-Sheetl 2 INVENTOR @Me/lt www {2-@JI A ORNEY Dec. 16, 1947.

Filed Oct. 28, 1945 Dec, 16, 1947. R B, COTTON Y 2,432,508

GLIDER PICK-UP DEVICE Filed Occ. 28, 1943 5 Sheets-Sheet 5 INVENTOR Dec. 16, 1947. R. B. COTTON 2,432,508

GLIDER PICK-UP DEVICE Filed 001'.. 28, 1943 5 Sheets-Sheet 4 INVENTOR KNOTS FEET FEET

Dec 16 1947 R. B. coTToN 2,432,508

GLIDER PICK-UP DEVICE Filed oct. 2s, 194s s sheets-sheet 5 @1920." c PLU/vette HCCELEEHT/ON VELoc/TY .Seconds l I ZA 3 Guam. /nym @19u m Tem/5L Pfg v INVENTOR o 2 i @wat @am TIME, t BY econ afs. ATTORNEY Patented Dec. 16, 1947 UNITED STATES PATENT OFFICE (Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 9 Claims.

1 The invention herein disclosed relates to glider pick-up apparatus of the type in which the `glider which is at rest to begin with, is .given a steady acceleration by energy obtained from a plane in iiight until it reaches the speed of the lplane, at which time a towline which has been picked up by the plane and which is connected `to the apparatus, is released therefrom, and is gripped by a device on the glider for the subsequent towing of the glider by the plane.

' The object of the apparatus is to transfer the Aenergy necessary for accelerating the glider with Vva steady and reasonable acceleration from the plane in flight, until the gilder attains the speed vof the plane and then to fix the towline for Vthe subsequent towing of the glider by the plane.

Another object is to accomplish the above object Without the necessity of carrying any of the ,during the latter part thereof, vthereby `continu- ,ouslyproviding only half of the steady-accelerating force on the glider, the other half beingrin .the meantime supplied to theglider directly from the plane through the other portion of the toW- ,lineipassed around the pulley.

A further object is to provide a take-up line connected between the hydraulic means and the towline vwhich is passed around the pulley on .the glider, means to release the towline from the take-up line when the glider reaches the speed ofthe plane, and means on the pulley to simultaneously grip the towline for the subsequent towing.

These and other Imore specific objects will become more apparent as the detail description of this invention proceeds. The preferred formof the apparatus is illustrated in the drawings wherein:

Fig. 1 shows the layout ofthe apparatus preparatory to the pick-up operation,

Fig. 2 is an enlarged view, partly in section, of the portable hydraulic and accumulator means,

Fig. 3 isa further enlargement of the main valve.

Figs. 4 ,and ;5 are sideand plan views, respec- 2 Ttively, of the pulley and gripping means attached tothe glider,

Fig. 6 -is a perspective View of the deck sheave, `,post and buffer assembly,

Fig. 7 is a cross-sectional view of the buifer and the releasable coupling between the towline Vand the take-up line, prior to release,

Fig. 8 is the same View with the parts in posi- .tion immediately after release, the broken line Iligure showing the towline end fitting broken .lavivay from the rest of the coupling an instant a er,

Fig. 9 is across-section taken at 9-9 of Fig. '7,

Figs. 10 to 13 are four consecutive views of the apparatus in itssuccessive stages during the .launching of the glider, and

Figs. 14,to 21 are graphical illustrations of the .characteristics obtained under one specific set of values used in the practice of this invention.

Referring more specifically to the several figures, the general layout of the apparatus may be seen in Fig. :1. The towline 3 is coupled at 32 to ,the Atake-upline 33 which passes from this coupling through the buer 3l, around the sheave 9 to the Ahydraulic Ymeans I0. From the coupling 3&2, the towline 3 is stretched back to the glider, passes around-the pulley 2 attached to the nose of the glider, then back to sheave post 8, then sideways Vto the `poles 5 and rB where it ends in a loop 4 hung loosely o-n the poles so that `it may be picked up by a pick-up hook depending from the Vplane which is to do the towing.

Figs. 2 and 3 show the details of the portable hydraulic mechanism I0 which has a hydraulic cylinder .I2 and piston I3 with piston rod I4, a set of Vpulleys I5 at the end of rod I4, and a similar set I6 Vat the closed end of the cylinder. The take-up line 433 is passed around these pulleys and may be anchored at one end to the frame at I'I, fthe other end being connected to the towline coupling as previously noted. The number of pulleys used -in each of the sets determines the mechanical advantage of the mechanism. The cylinder I2 is connected by pipe 26 to an accumulator I8 by Way of the main valve 21. Pipe 2G is connected Iby pipe 24 to the buffer tank 2|] by way of check valve 25. Another pipe 52, with a small globe valve therein, connects the tops of the `buler tank and the accumulator. Manual means is provided for lifting the check valve 25 off its seat. A sight gage 22 is provided on the buffer tank, and pressure gages I9 and 2| are mounted lin the buffer tank and the accumulator respectively. A vent pipe 23 controlled by a globe 3 valve is also provided in the top of the buier tank.

The main valve 21 is normally held in its open position by spring 29. The knob 28 is turnably mounted by a screw-thread connection to the valve stem guide so that it can be screwed down to move the valve against the spring pressure to its cio-sed position.

The details of the pulley attached to the glider may be seen in Figs. 4 and 5. The pulley 2 turns on a pin mounted in a yoke having a sleeve portion Eil with a spring Eli therein compressed between a shoulder thereof and an enlarged portion 55 on pin 5l passing therethrough and having eyelet 5S at the outer end, which is fastened to the nose of the glider. The inner end of the enlarged portion 55 has a shoe 59 normally pressed against the towline 3 on the pulley to grip the towline with a force suiiicient to overcome the pull on the towline necessary to tow the glider, but when a substantially greater force is applied to the towline such as is necessary during the glider acceleration, the spring 5B is further cornpressed to release the grip of the shoe 59 on the towline and permits the pulley 2 to turn freely, in accordance with the relative speeds oi the plane and glider during the acceleration period.

In Fig. 6, a plate 'l is shown which may comprise an assembly of the sheave S around which the take-up line is passed, a buffer against which the releasing element of the coupling 35 strikes at the appropriate time, and a sheave post S around which the towline is passed when initially stretched between the glider and the poles 5 and 5 on which its end loop is hung.

The details of the buiier and coupling may be seen in Figs. 7 to 9. The buffer sleeve 3d has an inner shoulder i3 against which the slidable collar member Il@ is normally resiliently held by spring El, the other end of which is biased against the fixed collar member fl. Take-up line 33 passes through this buier and is attached to the coupling plug d5 fitted against an inner shoulder in sleeve 38 and supporting one end of spring 'l therein, the other end of which biases a pin member le which extends through a collar xed in the end of the sleeve 38. The other end of sleeve 38 has a series of resilient prongs 39 extending therefrom around its periphery. These prongs have a collar lil mounted around their wedge formed ends so that when the collar is pushed over the wedged portions it brings the prongs radially toward the axis of the coupling. A peripheral shoulder formed by projections on the prongs is thereby moved radially within the circumference of the sleeve, while normally it has a greater diameter and is adaptable to lock over an internal shoulder 5l formed in a groove on the inside of the outer sleeve B comprising the other part of the coupling which is attached at il@ to the towline 3. The closed end of this outer sleeve forces the pin member i3 in against the pressure of spring lll when the coupling is locked. When the coupling is pulled in against the buffer 3d by the take-up line 33, the collar 35 in the buffer sleeve strikes the collar le which normally rests against the shoulder formed at the nose ll of the prong assembly. Movement of the prong ends into the hollow oi the sleeve 3d and collar where they are further wedged by the conical shape of the hollow in this collar, moves the collar til over the wedged portions oi' the prongs to draw the shoulder formed by the prongs inwardly out of the groove (il, and the pin member i8 assists in releasing the outer sleeve so as to break the connection and separate the coupling.

The operation of the apparatus is as follows:

Referring to Figs. l0 to 13, which represent four consecutive stages during the launching operation, Fig. 10 diagrammatically shows the starting set-up, with the pick-up plane 30 approaching the loop l of the towline. In Fig. 11 the towline has been picked up, the accelerating force applied to the glider is supplied jointly by the plane and the hydraulic mechanism.

The hydraulic system comprising the cylinder I 3, the accumulator I8 and the buiier tank 29 is so controlled that the hydraulic pressure will convey a suitable force through the take-up line 33 and will permit the take-up line to move either one way or the other in order to maintain a substantially constant force throughout both the take-up line and the towline 3 which is half of the total accelerating force applied to the glider. This is done by maintaining a pressure in the accumulator i3 over the hydraulic medium of sufcient amount to act as a cushion and maintain a substantially constant pressure in the hydraulic system during the operation of the piston I3 on its advance and retract strokes. The buffer tank 2li is provided for furnishing a reduced pressure in the cylinder at the beginning of the operation so as to prevent too sudden a shock on the glider upon its initial movement.

Thus at the beginning the plunger I3 moves on its advance stroke against a reduced pressure, thus furnishing a reduced force for the initial acceleration of the glider while the hydraulic fluid is moved through the pipe 28, pipe 24 and check valve 25 into the buer tank 2] against the low pressure of the air therein, valves 2l and 5l being closed at this time. As the piston I3 advances further and the pressure increases in the hydraulic system, it causes the valve 2l to open even against the high pressure in the accumulator. As soon as the valve 2l begins to open, spring 29 will raise it to its fully open position. Continued movement of the piston I3 then acts against the higher pressure in the accumulator to produce a substantially constant and reasonably large force to provide the necessary acceleration of the glider within the limits of the length of the towline for which it is designed. Fig. l2 shows the position of the piston on its retract stroke while maintaining the substantially constant force on the lines after about the middle of the acceleration period. In Fig. 13, the piston I3 is at the end of its retract stroke while the acceleration of the glider has suddenly dropped to practically zero. As a result of the decreased tension in the lines due to the sudden decrease of the acceleration of the glider and,

therefore, of the accelerating force, the spring 56 in the connection between the pulley 2 and the glider has expanded and the shoe 59 has gripped the towline 3 against the pulley while at the same time the coupling 35 has reached the buffer 34 and has been released thereby in accordance with the procedure previously outlined, with reference to Figs. 7 to 9. Thus the glider continues from this position in tow behind the tow plane with the towline fully extended therebetween. The charts shown in Figs. 14 to 21 show the characteristics of the plane and glider as well as the hydraulic plunger as obtained in one speciiic form of the invention used by the applicant. The curves are plotted against time in seconds. From these charts it may be seen that the airplane travels about sevenhundred feet during the launching operation while the glider travels three hundred and fifty feet with an acceleration of not exceeding 1.5 g. The initial plane velocity being at approximately 100 knots, gradually reduces to about 90 knots at the end of the acceleration period, the energy lost being transmitted through the towline to supply the constant force of acceleration on the glider with the assistance of thev hydraulic plunger which maintains this force at a substantially constant and desired amount. The mechanical advantage of the pulley arrangement on the specic form used in obtaining these characteristics was 2O to 1, by the use of 10 pulleys at each end of the hydraulic system.

Various other designs of this system may be made to suit the requirements. The device of the apparatus used here may be changed in form and dimensions as desired without departing from the scope of this invention which is dened in the appended claims.

The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

What is claimed is:

1. A glider launching and to-wing apparatus for enabling a plane in flight to take in tow a glider resting on the ground, comprising a pulley on the glider, a line passed around said pulley and stretched forward having a loop at one end for picking it up by the plane in flight and being anchored at the other end, adjustable take-up means for said line between its anchored end and the glider, a source of substantially constant force connected to said take-up means to provide a constant tension in said line equivalent to approximately half the desired acceleration force, means to break the line on the force source side of the pulley when the glider speed has reached that of the plane, and means o-n the glider for simultaneously gripping the line for its subsequent towing by the plane.

2. Apparatus as defined in claim 1 including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane do-es not have to sweep dangerously low over the glider to pick up the loop.

3. Apparatus as dened in claim 1 including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane does not have to sweep dangerously low over the glider to pick up the loop, and a sheave in front of the glider around which the anchored end of the line is passed and extends to the other side of the glider axis where said line take-up means is located.

4. Apparatus as dened in claim l including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane does not have to sweep dangerously low over the glider to pick up the loop, and a sheave in front of the glider around which the anchored end of the line is passed and extends to the other side oi the glider axis where said line take-up means is located, the said line take-up means including a. pressure accumulator means and a hydraulic means for pulling in or paying out the line in accordance with the relative speeds of the glider and plane during the glider acceleration period.

5. Apparatus as dened in claim 1 including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane does not have to sweep dangero-usly low over the glider to pick up the loop, and a sheave infront of the glider around which the anchored end of the line is passed and extends to the other side of the axis Where said line take-up means is located, the said line take-up means including a pressure accumulator means and a hydraulic means for pulling in or paying out the line in accordance with the relative speeds of the glider and plane during the glider acceleration period, said accumulator means storing and returning the hydraulic medium under substantially constant pressure to the hydraulic means.

6. Apparatus as dened in claim 1 including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane does not have to sweep dangerously low over the glider to pick up the loop, and a sheave in front of the glider around which the anchored end of the line is passed and extends to the other side of the glider axis where said line take-up means is located, the said line take-up means including a pressure accumulator means and a hydraulic means for pulling in or paying out the line in accordance with the relative speeds of the glider and plane during the glider acceleration period, said accumulator means storing and returning the hydraulic medium under substantially constant pressure to the hydraulic means, auxiliary buier means under less pressure for supplying a smaller initial pressure to the hydraulic means at the beginning of its operation, and means for cutting off the connection between the hydraulic means and the accumulator during this initial period so as to supply only a smaller initial acceleration force to the glider at the beginning of the acceleration period to reduce the starting shock.

7. Apparatus as dened in claim 1 including a sheave post in front of the glider around which the loop end of the line is passed and means for suspending the loop at a distance to one side of the glider axis so that the plane does not have to sweep dangerously low over the glider to pick up the loop, and wherein the other end of the line is passed around a sheave and extends to the other side of the glider axis where said force source is located, the said force source including a pressure accumulator means and a hydraulic means for pulling in or paying out the line in accordance with the relative speeds of the glider and plane during the glider acceleration period, the said means for breaking the line comprising a releasable coupling and buffer through which the line operates and against which the coupling strikes at the time when the line is fully pulled in at the end of the acceleration period, and means for releasing said coupling responsive to said contact between the coupling and the buier.

8. In a glider launching and towing apparatus, a plate including a sheave journaled at the front thereof, a buier means mounted on said plate to the rear of said journaled sheave, and a sheave post mounted on one side of said plate, said buffer means comprising a sleeve xed to the plate and having a xed collar in its forward end and an internal shoulder at the rear end, a slidable collar within the sleeve and a spring between said two collars normally urging the slidable collar against said shoulder,

n: 119; In aglider launchingandtowingapparatus,l sleevemember within -thefcylindenlmovement of a plate including a sheave journaledrat the front Y thereof,a-fbuerfmountedeon'said-plate to the `v.the collar backward -over vthe wedgedportions :drawing the prongs Ytowards the axis and Withrear kof said-journaledsheavefa-nd'avrsheave posta` s draWingtheshoulder formedby saidrprongs from at -one side thereof,-a-takeup'line passed from f5 fthe groove in the cylinder, thereby releasing the 'one side aroundftheysheave'.and through the buff.; f couplingandfa spring-pressed collar within said fer,y a releasable-Acoupling..connectingthe end fofr louier/` having .an opening therein `suiiiciently v:large to permit -the ends' of the prongsto enter 1 cluding a closedfendicylinder:.connected at its.. 'z- -thereingwhile the collaron the prongs is moved Y. rclosed end tothe towline,.asleeve'membergslid.10.,bythe outer` edge of: the collar inthe Vbuffer to s: ably tting Within this cylinder, saidsleeve meme:- ber having a` collar. xed in the'end which ts into the,cy1in der,:a pin' member'in-said sleeve.

release ,said coupling, theV cylinder-being assisted A.gin its releasing operation bythe pressure of said -i'pin member against the closed end of the member passing throughysaidrollar and having w cylinder.

= ashoulder normally resting against said collar, 15

.- against a; plug lmember which @isfconnected rto r the take-np` line Aand whichirests against an `having `exible prongs extending circumfer- ROBERT B. COTTON. 'a spring having one endgthereofbiasing lsaid pin member, the other -endoi-.Said Spring resting :,REFERENCES CITED *The following references are of record in the file of this patent:

internal shoulder ing ,said sleeve, Afthe sleeve 20 i i UNITED. STATES PATENTS entiallyabout said.' take-up Vlineand being of Number Name Date wedge form at their ends,- acollar vtting around. 1,494,910 Hench May 20, 1924 i said wedged portions normally resting against a 2,369,518 Ballard j Feb. 13, 1945 i said prongs, the icylincler Ahaving arr-internal .1 groove formed Anear its vopen end,V anda.shoulder-"1??r normally tting in' said groove formed by projec- Y tions on theprongs soas 'tonormallylock the shoulderformed-byenlargements atithe ends of 25 OTHER REFERENCES 'z Publication, Popular Mechanics/pages 14 and 15 of Oct. 1942.

-Popu1ar Mechanicsf? Oct. 1942, page 15.

Certiicate of Correction Patent N 0. 2,432,508.

numbered patent requirin correct1on as follows: Column 6, line 50, claim 7, cancel the Word wherein and insert mstead a sheaee in front of the glider around which; same line, cancel other and insert instead anchored; line 5l, cancel around a sheave line 52, cancel force and insert instead Zine take-ap means; line 53, cancel source, first occurrence; same line, cancel force source and insert instead Zine take-n means; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the casein the Patent Office.

Signed and sealed this 23rd day of March, A. D. 19448.

THOMAS F@ MURPHY, 

